1 /****************************************************************************** 2 3 (c) 2007 Network Appliance, Inc. All Rights Reserved. 4 (c) 2009 NetApp. All Rights Reserved. 5 6 NetApp provides this source code under the GPL v2 License. 7 The GPL v2 license is available at 8 http://opensource.org/licenses/gpl-license.php. 9 10 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 11 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 12 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 13 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 14 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 15 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 16 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 17 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 18 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 19 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 20 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 21 22 ******************************************************************************/ 23 24 #include <linux/tcp.h> 25 #include <linux/slab.h> 26 #include <linux/sunrpc/xprt.h> 27 #include <linux/export.h> 28 #include <linux/sunrpc/bc_xprt.h> 29 30 #ifdef RPC_DEBUG 31 #define RPCDBG_FACILITY RPCDBG_TRANS 32 #endif 33 34 /* 35 * Helper routines that track the number of preallocation elements 36 * on the transport. 37 */ 38 static inline int xprt_need_to_requeue(struct rpc_xprt *xprt) 39 { 40 return xprt->bc_alloc_count > 0; 41 } 42 43 static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n) 44 { 45 xprt->bc_alloc_count += n; 46 } 47 48 static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n) 49 { 50 return xprt->bc_alloc_count -= n; 51 } 52 53 /* 54 * Free the preallocated rpc_rqst structure and the memory 55 * buffers hanging off of it. 56 */ 57 static void xprt_free_allocation(struct rpc_rqst *req) 58 { 59 struct xdr_buf *xbufp; 60 61 dprintk("RPC: free allocations for req= %p\n", req); 62 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 63 xbufp = &req->rq_private_buf; 64 free_page((unsigned long)xbufp->head[0].iov_base); 65 xbufp = &req->rq_snd_buf; 66 free_page((unsigned long)xbufp->head[0].iov_base); 67 kfree(req); 68 } 69 70 /* 71 * Preallocate up to min_reqs structures and related buffers for use 72 * by the backchannel. This function can be called multiple times 73 * when creating new sessions that use the same rpc_xprt. The 74 * preallocated buffers are added to the pool of resources used by 75 * the rpc_xprt. Anyone of these resources may be used used by an 76 * incoming callback request. It's up to the higher levels in the 77 * stack to enforce that the maximum number of session slots is not 78 * being exceeded. 79 * 80 * Some callback arguments can be large. For example, a pNFS server 81 * using multiple deviceids. The list can be unbound, but the client 82 * has the ability to tell the server the maximum size of the callback 83 * requests. Each deviceID is 16 bytes, so allocate one page 84 * for the arguments to have enough room to receive a number of these 85 * deviceIDs. The NFS client indicates to the pNFS server that its 86 * callback requests can be up to 4096 bytes in size. 87 */ 88 int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs) 89 { 90 struct page *page_rcv = NULL, *page_snd = NULL; 91 struct xdr_buf *xbufp = NULL; 92 struct rpc_rqst *req, *tmp; 93 struct list_head tmp_list; 94 int i; 95 96 dprintk("RPC: setup backchannel transport\n"); 97 98 /* 99 * We use a temporary list to keep track of the preallocated 100 * buffers. Once we're done building the list we splice it 101 * into the backchannel preallocation list off of the rpc_xprt 102 * struct. This helps minimize the amount of time the list 103 * lock is held on the rpc_xprt struct. It also makes cleanup 104 * easier in case of memory allocation errors. 105 */ 106 INIT_LIST_HEAD(&tmp_list); 107 for (i = 0; i < min_reqs; i++) { 108 /* Pre-allocate one backchannel rpc_rqst */ 109 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL); 110 if (req == NULL) { 111 printk(KERN_ERR "Failed to create bc rpc_rqst\n"); 112 goto out_free; 113 } 114 115 /* Add the allocated buffer to the tmp list */ 116 dprintk("RPC: adding req= %p\n", req); 117 list_add(&req->rq_bc_pa_list, &tmp_list); 118 119 req->rq_xprt = xprt; 120 INIT_LIST_HEAD(&req->rq_list); 121 INIT_LIST_HEAD(&req->rq_bc_list); 122 123 /* Preallocate one XDR receive buffer */ 124 page_rcv = alloc_page(GFP_KERNEL); 125 if (page_rcv == NULL) { 126 printk(KERN_ERR "Failed to create bc receive xbuf\n"); 127 goto out_free; 128 } 129 xbufp = &req->rq_rcv_buf; 130 xbufp->head[0].iov_base = page_address(page_rcv); 131 xbufp->head[0].iov_len = PAGE_SIZE; 132 xbufp->tail[0].iov_base = NULL; 133 xbufp->tail[0].iov_len = 0; 134 xbufp->page_len = 0; 135 xbufp->len = PAGE_SIZE; 136 xbufp->buflen = PAGE_SIZE; 137 138 /* Preallocate one XDR send buffer */ 139 page_snd = alloc_page(GFP_KERNEL); 140 if (page_snd == NULL) { 141 printk(KERN_ERR "Failed to create bc snd xbuf\n"); 142 goto out_free; 143 } 144 145 xbufp = &req->rq_snd_buf; 146 xbufp->head[0].iov_base = page_address(page_snd); 147 xbufp->head[0].iov_len = 0; 148 xbufp->tail[0].iov_base = NULL; 149 xbufp->tail[0].iov_len = 0; 150 xbufp->page_len = 0; 151 xbufp->len = 0; 152 xbufp->buflen = PAGE_SIZE; 153 } 154 155 /* 156 * Add the temporary list to the backchannel preallocation list 157 */ 158 spin_lock_bh(&xprt->bc_pa_lock); 159 list_splice(&tmp_list, &xprt->bc_pa_list); 160 xprt_inc_alloc_count(xprt, min_reqs); 161 spin_unlock_bh(&xprt->bc_pa_lock); 162 163 dprintk("RPC: setup backchannel transport done\n"); 164 return 0; 165 166 out_free: 167 /* 168 * Memory allocation failed, free the temporary list 169 */ 170 list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list) { 171 list_del(&req->rq_bc_pa_list); 172 xprt_free_allocation(req); 173 } 174 175 dprintk("RPC: setup backchannel transport failed\n"); 176 return -ENOMEM; 177 } 178 EXPORT_SYMBOL_GPL(xprt_setup_backchannel); 179 180 /** 181 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures. 182 * @xprt: the transport holding the preallocated strucures 183 * @max_reqs the maximum number of preallocated structures to destroy 184 * 185 * Since these structures may have been allocated by multiple calls 186 * to xprt_setup_backchannel, we only destroy up to the maximum number 187 * of reqs specified by the caller. 188 */ 189 void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) 190 { 191 struct rpc_rqst *req = NULL, *tmp = NULL; 192 193 dprintk("RPC: destroy backchannel transport\n"); 194 195 if (max_reqs == 0) 196 goto out; 197 198 spin_lock_bh(&xprt->bc_pa_lock); 199 xprt_dec_alloc_count(xprt, max_reqs); 200 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 201 dprintk("RPC: req=%p\n", req); 202 list_del(&req->rq_bc_pa_list); 203 xprt_free_allocation(req); 204 if (--max_reqs == 0) 205 break; 206 } 207 spin_unlock_bh(&xprt->bc_pa_lock); 208 209 out: 210 dprintk("RPC: backchannel list empty= %s\n", 211 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 212 } 213 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); 214 215 /* 216 * One or more rpc_rqst structure have been preallocated during the 217 * backchannel setup. Buffer space for the send and private XDR buffers 218 * has been preallocated as well. Use xprt_alloc_bc_request to allocate 219 * to this request. Use xprt_free_bc_request to return it. 220 * 221 * We know that we're called in soft interrupt context, grab the spin_lock 222 * since there is no need to grab the bottom half spin_lock. 223 * 224 * Return an available rpc_rqst, otherwise NULL if non are available. 225 */ 226 struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt) 227 { 228 struct rpc_rqst *req; 229 230 dprintk("RPC: allocate a backchannel request\n"); 231 spin_lock(&xprt->bc_pa_lock); 232 if (!list_empty(&xprt->bc_pa_list)) { 233 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, 234 rq_bc_pa_list); 235 list_del(&req->rq_bc_pa_list); 236 } else { 237 req = NULL; 238 } 239 spin_unlock(&xprt->bc_pa_lock); 240 241 if (req != NULL) { 242 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 243 req->rq_reply_bytes_recvd = 0; 244 req->rq_bytes_sent = 0; 245 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 246 sizeof(req->rq_private_buf)); 247 } 248 dprintk("RPC: backchannel req=%p\n", req); 249 return req; 250 } 251 252 /* 253 * Return the preallocated rpc_rqst structure and XDR buffers 254 * associated with this rpc_task. 255 */ 256 void xprt_free_bc_request(struct rpc_rqst *req) 257 { 258 struct rpc_xprt *xprt = req->rq_xprt; 259 260 dprintk("RPC: free backchannel req=%p\n", req); 261 262 smp_mb__before_clear_bit(); 263 WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 264 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 265 smp_mb__after_clear_bit(); 266 267 if (!xprt_need_to_requeue(xprt)) { 268 /* 269 * The last remaining session was destroyed while this 270 * entry was in use. Free the entry and don't attempt 271 * to add back to the list because there is no need to 272 * have anymore preallocated entries. 273 */ 274 dprintk("RPC: Last session removed req=%p\n", req); 275 xprt_free_allocation(req); 276 return; 277 } 278 279 /* 280 * Return it to the list of preallocations so that it 281 * may be reused by a new callback request. 282 */ 283 spin_lock_bh(&xprt->bc_pa_lock); 284 list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list); 285 spin_unlock_bh(&xprt->bc_pa_lock); 286 } 287 288